1. Field of the Invention
The present invention relates to dual mode flush valve assembly selectively operable in a full or partial flush mode for use with a toilet flush tank assembly.
2. Description of the Prior Art
Normally the flush cycle of most toilets is initiated by moving a lever to unseat a plug or seal from the bottom of a storage tank to release the stored water into the toilet bowl. A siphonic action siphons the water out of the bowl and into a drain pipe which carries the flushed contents to the sewer system. The normal capacity of storage tanks used for this purpose is sufficient to initiate the siphonic action and to refill the trap in the bowl once the flush cycle has begun. As the remaining water drains from the tank into the trap, the plug or seal reseal the tank and fresh water fills the tank for the succeeding flush cycle.
Most conventional toilets use approximately five gallons of water per flush. Many efforts have been developed to reduce this water consumption. These include such simple measures as placing a brick or a weighted plastic bottle in the tank to displace a volume of water; bending the float rod downward to reduce the amount of water required to fill the tank to the operating level; or placing a baffle in the tank against a side wall or around the drain hole to keep some of the water in the tank. More complex measures include using specially designed shallow trap model toilets, or models which use air pressure or mineral oil as a flushing agent. These alternative methods and devices are generally either prohibitively expensive or save water at the expense of flushing performance, disadvantages which are normally unacceptable.
Detjen, U.S. Pat. No. 4,216,555, shows a dual flush system tank operable in either a full flush or a partial flush. A control handle is actuated normally to produce a full flush. If a partial flush is desired, the control handle is held in a depressed condition for two or three seconds before release to produce a partial flush. A partial flush is produced by a buoyant reseating weight which will float down with the falling level of liquid in the tank to depress the flush ball and prematurely reseat the flush ball with only part of the liquid discharged from the tank. For a full flush, the control handle is released and immediately re-engaged before the buoyant reseating weight moves downwardly in the tank and latched against premature seating of the flush ball.
Renz, U.S. Pat. No. 4,328,596, discloses a system to drain a toilet tank either partially or completely.
Kloner, U.S. Pat. No. 4,485,501, shows a toilet flush mechanism to conserve water by directional at rotation of the flushing handle to actuate a first lever initiating the discharge of a full tank of water or actuate a second lever initiating the discharge of a predetermined fraction of the water in the full tank.
Phripp, U.S. Pat. No. 4,032,997, discloses a flush regulator for use in a toilet flush tank to regulate the outflow from the flush tank through an outlet pipe.
Meier, U.S. Pat. No. 4,486,906, shows a flush valve assembly for use in a toilet storage tank. A valve cup having a float is rotatably mounted within a housing including an elongated horizontal slot. The valve cup contains water when the storage tank is full, and upon initiation of a flush cycle, the float engages an abutment which is secured to a valve shaft to retard the rate of descent of the valve shaft by floating downwardly in the valve cup as the water drains from the horizontal slot. The valve cup can be rotated to variably restrict the slot to increase or decrease the rate of descent of the valve shaft to seal the tank as soon as the trap has been refilled.